Computer games are purported to be effective instructional tools that enhance motivation and improve engagement. The aim of this study was to investigate how tertiary student experiences change when instruction was computer game based compared to lecture based, and whether experiences differed between high and low achieving students. Participants consisted two cohorts enrolled in a first year university course (Cohort 1, traditional: male=42, female=17; Cohort 2, computer game: male=42, female=7). Cohort 1 experienced course content as traditional lectures, Cohort 2 experienced course content embedded within a computer game. Csikszentmihalyi's experience sampling method was used to sample experiences of students for each cohort during instruction. Results showed that the computer game group were more challenged and valued the activity more than the traditional group, but were inclined to wish they were doing something else. High achieving students during game mode showed greater concentration but found it harder to concentrate and found game mode more sociable and lecture mode more boring. High achievers perceived greater success for lecture mode and found lectures more satisfying. Individual profiles of high and low achieving students for each mode indicated that games afforded better experiences for low achieving students but poorer experiences for high achieving students.